[Kinetic tracer studies on protein synthesis during infancy using chemically defined diets containing 15N-lysine as a tracer (author's transl)].
A four-month-old infant with exocrine pancreas insufficiency was fed exclusively on a chemically defined diet. The amino acid formulation of this diet (a supplemented casein hydrolyzate) corresponds to that of breast milk. The 15N labeled lysine tracer (97.4 atom-%) was included in the diet without changing its chemical score. A trace dose of 2.22 mg/kg body weight was applied for 5 days after the infant had been maintained on a chemically defined diet for 11 weeks. Urine was collected over a period of 170 h. The compartment theory was used to calculate the following metabolic data. Cumulative renal 15N excretion showed that nitrogen retention was 90.8%. Protein synthesis amounted to 10.34 g kg-1 d-1 compared with a protein breakdown rate of 8.97 kg-1 d-1. Net protein gain in this infant was about 5.5 g d-1 corresponding to a rate of 1.38 kg-1 d-1 or 13.3% of the synthesis rate. The metabolic pool amounted to 4.96 g N kg-1 d-1. 75.99 mg N kg-1 h-1 was metabolized, mainly to protein, and only about 10% was excreted with the urine.
D000596:Amino Acids / Q000378:metabolism; D010188:Exocrine Pancreatic Insufficiency / Q000000981:diagnostic imaging / Q000178:diet therapy* / Q000378:metabolism; D005526:Food, Formulated / Q000032:analysis*; D006801:Humans; D007223:Infant; D007225:Infant Food; D007700:Kinetics; D008239:Lysine / Q000008:administration & dosage*; D008297:Male; D009590:Nitrogen Radioisotopes / Q000008:administration & dosage*; D014176:Protein Biosynthesis; D011859:Radiography
D000596:Amino Acids; D009590:Nitrogen Radioisotopes; D008239:Lysine
Tracerkinetische Untersuchungen zur Proteinsynthese im Säuglingsalter mit [alpha 15 N] L-Lysin markierter chemisch definierter Nahrung.